package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class  ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Autowired
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    /**
     * 缓存根据id查询店铺的功能
     */
    @Override
    public Result queryById(Long id) {
        //缓存穿透
        //Shop shop = queryWithPassThrough(id);
        //Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id, Shop.class,id2 -> getById(id2),CACHE_SHOP_TTL,TimeUnit.MINUTES);
        //Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //用互斥锁实现缓存击穿
        //Shop shop = queryWithMutex(id);

        //用逻辑过期解决缓存击穿
        //Shop shop = queryWithLogicalExpire(id);
        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);


        if (shop == null) {
            return Result.fail("店铺不存在！");
        }
        //返回
        return Result.ok(shop);
    }

    //线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    /**
     * 逻辑过期的代码
     */
    public Shop queryWithLogicalExpire(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1. 从redis查询缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2. 判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //3. 不存在 说明不是热点key 没有这个活动
            return null;
        }
        //4命中需要判断过期时间 将json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        JSONObject data = (JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.1 未过期，直接返回店铺信息
            return shop;
        }
        //5.2 过期，需要异步缓存重建
        //6缓存重建
        //6.1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY+id;
        boolean isLock = tryLock(lockKey);
        //6.2 判断是否获取锁成功
        if (isLock) {
            //6.3 成功 开启线程异步 （返回商铺过期信息）
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    //重建缓存
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }
        //6.4 失败 （返回商铺过期信息）
        return shop;
    }

    public Shop queryWithMutex(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1. 从redis查询缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2. 判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3. 存在 直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //解决缓存穿透--无效请求返回控制  等价于shopJson == ""
        if (shopJson != null){
            return null;
        }
        //4 实现缓存重建
        //4.1获取互斥锁
        String lockKey = "lock:shop:"+id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2判断是否获取成功
            if ( !isLock) {
                //4.3失败，休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4. 不存在 根据id查询数据库 MP内置方法
            shop = getById(id);
            //5. 数据库没有这个数据，返回404错误
            if (shop == null) {
                //解决缓存穿透--缓存空值
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //6. 数据库有 写入redis 并返回
            String jsonStr = JSONUtil.toJsonStr(shop);
            stringRedisTemplate.opsForValue().set(key,jsonStr,CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7释放互斥锁
            unlock(lockKey);
        }
        //8返回
        return shop;
    }

    /**
     * 保存解决缓存穿透的代码
     */
    public Shop queryWithPassThrough(Long id){
        String key = CACHE_SHOP_KEY + id;
        //1. 从redis查询缓存
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2. 判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3. 存在 直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        //解决缓存穿透--无效请求返回控制  等价于shopJson == ""
        if (shopJson != null){
            return null;
        }
        //4. 不存在 根据id查询数据库 MP内置方法
        Shop shop = getById(id);
        //5. 数据库没有这个数据，返回404错误
        if (shop == null) {
            //解决缓存穿透--缓存空值
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //6. 数据库有 写入redis 并返回
        String jsonStr = JSONUtil.toJsonStr(shop);
        stringRedisTemplate.opsForValue().set(key,jsonStr,CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }

    //尝试获取锁
    private boolean tryLock(String key){
        //setNx  命令行中返回的是0和1 spring帮我们封装成Boolean
        Boolean aBoolean = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        //拆箱可以会导致null指针
        return BooleanUtil.isTrue(aBoolean);
    }

    //释放锁
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    /**
     * 给店铺信息添加逻辑过期时间
     */
    public void saveShop2Redis(Long id,Long expireSeconds){
        //1.查询店铺数据
        Shop shop = getById(id);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }



    /**
     * 根据id修改店铺信息 先操作数据库 再操作redis
     */
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空！");
        }
        //1. 更新数据库
        updateById(shop);
        //2. 删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    //根据店铺分类分页查询
    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询 （不用就根据旧方法-数据库）
        if (x == null || y == null) {
            //不需要根据坐标查询 按数据库查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            //返回数据
            return Result.ok(page);
        }
        //2.计算分页参数
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        //3.查询redis 按照距离排序，分页  结果：shopId 和 distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo()  //GEOSEARCH key ByLONLAT x y BYRADIUS 10 WITHDISTANCE
                .search(
                        key,
                        GeoReference.fromCoordinate(x, y),
                        new Distance(5000),  //米                                            end结束页
                        RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
                );
        //4.解析出id
        //from
        if (results == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent(); //从0到end
        //判空
        if (list.size() <= from){
            return Result.ok(Collections.emptyList());
        }
        List<Long> ids = new ArrayList<>(list.size());
        Map<String,Distance> distanceMap = new HashMap<>(list.size());
        //截取从from - end 部分
        list.stream().skip(from).forEach(result -> {
            //店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        //5.根据id查询店铺信息
        String idStr = StrUtil.join(",",ids);
        List<Shop> shopList = query().in("id", ids).last("order by field(id," + idStr + ")").list();
        for (Shop shop : shopList) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shopList);
    }
}
